text: class TestPersistence(object):
  
      def __init__(self):
          self._data_points = []
  
      def get_data_points(self, run_id=None):
          if run_id:
              return [dp for dp in self._data_points if dp.run_id is run_id]
          return self._data_points
  
      def persist_data_point(self, data_point):
          self._data_points.append(data_point)
  
      def close(self):
          pass
  